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OSUNIPHYS$134\mathrm{.}4.$WA$\mathrm{.}028.$

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Laser light is passed through a rod made out of a material with an index of refraction of $1\mathrm{.}56,$ a length $L=45\mathrm{.}0cm,$ and square cross section of length $h=3\mathrm{.}00mm$ on a side as shown in the figure. If the light enters at the center of the rod with an angle of incidence in air of ${}_1=51\mathrm{.}2,$ determine the number of total internal reflections before it emerges from the opposite end of the rod.

Have you drawn a figure showing all angles and distances?

Can you write Snell's Law for the case where light is entering the rod and also for the first case where the light strikes the side of the rod?

How is the angle of incidence in the material related to the angle of refraction in the material?

How is the critical angle for the material in the rod related to the angle of refraction for the rod?

How do you know that total internal reflection will occur rather than refraction into the air outside the rod?